Update building.md

docs/building.md

@@ -4,13 +4,18 @@
 
 ## Build and install Intel SGX SDK
 
+We are currently using SGX SDK version 2.13. 
+
+Below is a sequence of commands that builds SDK and installs it into /opt/intel directory.
+
+
 ```bash
 git clone -b sgx_2.13 --depth 1 https://github.com/intel/linux-sgx
 cd linux-sgx
 make preparation
 sudo make sdk_install_pkg_no_mitigation
 cd /opt/intel
-sudo sh -c 'echo yes | /linux-sgx/linux/installer/bin/sgx_linux_x64_sdk_*.bin'
+sudo sh -c 'echo yes | /linux-sgx/linux/installer/bin/sgx_linux_x64_sdk_*.bin
 sudo make psw_install_pkg
 sudo cp /linux-sgx/linux/installer/bin/sgx_linux_x64_psw*.bin .
 sudo ./sgx_linux_x64_psw*.bin --no-start-aesm